Load calculation?

Going through load calcs for my house w/ proposed addition, as I'll be getting a new main panel before the addition.

Wondering how I calculate the load of a garage? Not a workshop, no living space, just a standard garage used as an average garage. General lighting load of 3W/SF? Less since it doesn't have/need much light?

So, once I do the load calculation, is there a NEC mandated additional amount of ampacity required? (IE: If my load calcs came up with 62 AMPs, does NEC say I need 62+20% minimum for service?)

I did come up with a little over 60 amps. Not too much load when the dryer, WH and stove are all gas. I currently have 100 AMP service and don't see EVER adding any more high load items than what I calculated for. I doubt we'd ever add a hot tub, no reason to go to Electric WH or Stove.

I'll need to move the service drop when I do have the panel upgraded. But that fun will come later.

You need to do the electric work per the NEC that is being utilized by te local jurisdiction at the time you build. But you can always wire what some call code plus. all GFCI all AFCI ect.....but check with the local jurisdiction to see what NEC is presently in use in your area.